A special edition of the March 1, 1918 Watchtower magazine, which was also referred to as "ZG" ("Z" standing for Zion's Watch Tower and "G" represented the 7th volume of Studies in the Scriptures). This special issue of the Watchtower magazine contained a paperback version of The Finished Mystery with additional commentary. At this time, the president of the Watchtower Society was J.F. Rutherford who had succeeded C.T. Russell after Russell's death in 1916. Rutherford later gave the movement the name Jehovah's Witnesses in 1931.